The changeover to ICD-10 medical diagnosis codes could complicate tasks in emergency departments.

Effective today, the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) have replaced ICD-9-CM, volumes 1 and 2, under a final rule from the US Centers for Medicare and Medicaid Services (CMS).

CMS contends that the new diagnostic codes will modernize patient care and help prevent medical billing fraud, as the ICD-10 codes are longer and more exact than the ICD-9 codes they replace. ICD-10 also includes more than 68,000 diagnostic codes, compared with the 14,000 in ICD-9.

But when researchers from the University of Illinois at Chicago looked at more than 24,000 clinical encounters in the emergency room (ER), they found that nearly a quarter could be assigned incorrect ICD-10 codes if CMS recommendations were followed.

The investigators also determined that 27% of 1830 ICD-9 indicator codes commonly used by emergency physicians had convoluted mappings to ICD-10 codes that could pose problems for clinical documentation, reimbursement, disease reporting, and justifying hospital admissions.

Some of the ER ICD-9 codes they examined in a subset of a 2010 Illinois Medicaid database simply didn’t map at all.

“Depending on the analytic programs that the pharmacies use to predict how much medications to store and how complex the transition to ICD-10 is, pharmacies might have shortages of medications due to inaccurate reports and algorithms,” study author Andrew Boyd, MD, explained to Pharmacy Times in an e-mail. “This challenge will last until we have enough historical data in ICD-10 to conduct all reports in the new diagnosis coding system.”

To assist clinicians with the expanded codes, the research team created a free online conversion tool that provides ICD-9 to ICD-10 code mappings.

Prior publications generally recommend migrating the data forward to ICD-10 or backwards to ICD-9, but not in both directions at the same time—resulting in missing data, Dr. Boyd explained.

“Due to the complex nature of the transition to ICD-10 for some codes, if pharmacists interpret reports of diseases or assist in the ordering of the medications, engage with your information technology team to explain how pharmacists use the reports and the reason why you are using the reports,” Dr. Boyd noted. “…If the pharmacy perspective is not included during the preparation, the quality of the data may be compromised.”

This research titled “The complexity and challenges of the International Classification of Diseases, Ninth Revision, Clinical Modification to International Classification of Diseases, 10th Revision, Clinical Modification transition in EDs” was published in The American Journal of Emergency Medicine